Conventionally proposed are some apparatuses that apply image processing to camera images captured by a plurality of onboard cameras that are mounted on a vehicle, to generate a synthetic image providing a view of the conditions surrounding a vehicle from an optional virtual viewpoint such as immediately above or behind the vehicle, and to display the synthetic image on a display.
With such an apparatus, a camera image may be misaligned with respect to the position where the image is intended to be synthesized in the synthetic image, due to individual differences among the individual onboard cameras or slight errors at the position where the cameras are mounted. Workers of dealers, for example, therefore calibrate the onboard cameras to correct such misalignment.
To calibrate cameras, a worker displays the images captured by the respective onboard cameras while markers having a certain shape are placed around the vehicle, and sets some parameters indicating the positions of the images of the respective markers found in the images, for example (see Patent Literature 1, for example).